PB2094: PRIMARY MEDIASTINAL B-CELL LYMPHOMA: EXPERIENCE OF THE HEMATOLOGY DEPARTMENT OF SFAX
Authors: M. Charfi, G. Abichou, I. Frikha, L. Khelifa, L. Ghorbel, I. Saguem, W. Feki, H. Ben salah, T. Boudawara, Z. Mnif, J. Daoud, M. Elloumi
Journal: HemaSphere (2022)

Background: Primary mediastinal B-cell lymphoma (PMBCL) is a rare lymphoma subtype that usually occurs in adolescents and young adults. Its clinical features resemble classical Hodgkin lymphoma. The prognosis of most patients with PMBCL is very good. Thus, there is no standard of care for this group of lymphoma. Aims: The aim of this study is to describe the epidemiological, clinical and therapeutics characteristics of this disease in our center. Methods: This retrospective study involved untreated patients with PMBCL diagnosed between January 2008 and December 2019 in the Hematology department of Sfax in Tunisia. Diagnosis was made on the basis of histopathological examination with mandatory immunohistochemical staining. Ann Arbor system was used for staging. Age adjusted international Prognostic Index (aa-IPI) score was used to evaluate prognosis. Patients were treated with immunotherapy combined with chemotherapy (CHOP+/-R, ACVBP+/-R). For patients aged 60 and younger with aaIPI>1, a consolidative therapy by autologous stem cell transplantation (ASCT) was indicated. We evaluated the response with the International Working Group (IWG) Response Criteria for NHL 1999. Kaplan Meier method was used to estimate overall survival (OS) and event-free survival (EFS). Results: Twenty-nine patients with PMBCL were identified during the study period. The median age was 34 years (range:17-64) and Sex-ratio was 0,36. The most common revealing symptoms were dyspnea (45%) followed by cough (21%). B symptoms were reported in 62% of cases. Approximately half of the patients (48%) presented with upper vena cava syndrome and bulky mediastinal disease was noted in 90 % of cases (n=26 patients). 30% of our patients had a performance status>1, 76 % had elevated Lactates Dehydrogenases and 48% had advanced stage. aaIPI was high (>1) in 45% of the cases. All the patients were treated with an immuno-chemotherapy (R-CHOP=23, R-ACVBP=6). The overall response rate was 86% and complete remission was noted in only 38% of cases. ASCT was indicated for 13 patients (45%) but only four patients (31%) underwent the procedure. Eight patients had a radiation therapy to mediastinal residual mass after chemotherapy. 14% of patients had refractory disease and 11% relapsed. OS and EFS at 5 years were 76% and 70%, respectively. Summary/Conclusion: Our epidemiological and clinical data are globally similar to reported studies except for systemic symptoms affecting only 20 % of cases and advanced stages, which are less frequent (20-30%) in the literature. Complete remission rate in our study is insufficient compared to data from the literature (80 %).The response was unfortunately assessed by computed tomography because of non-availability of PET-CT until 2020. Five years OS and EFS were lower than the values reported in other series in literature (OS: 80-90 %; EFS: 78-89%). These results may be improved by the assessment of the response by PET-CT, using more intensified regimens and the availability of ASCT especially in high-risk patients and in patients who achieved only PR.